1. Field of the Invention
The present invention relates generally to a digital table display system, and in particular, to a multi-resolution digital table display system.
2. The Prior Arts
Digital tables, capable of dealing with documentary jobs and displaying digital images, are considered a solution for restricted working space, and attract more attention for future development. Mark Ashdown published a thesis in 2002, titled “The Escritoire: A personal Projected Display for Interacting with Documents”. Mark proposed in the thesis to project a digital document onto a digital table by a projection device and a reflective mirror. The whole system disclosed in the thesis was specifically designed in consideration of the special structure of human vision systems. Human visions can be divided into two kinds, which are known as foveal vision and peripheral vision respectively. The foveal vision is also known as direct vision, which is suitable for identifying details of images or color information and not suitable for identifying shadows. On the contrary, the peripheral vision is responsible for identifying shadows. In this manner, if one stares at an object for a long time, his peripheral vision gradually works less. For example, when one among a plurality of words of a letter is being stared at with more and more concentration, the other words would be more and more blurred.
According to the special structure of human vision systems, the conventional digital table employs two projection devices. One projection device is responsible for those relatively large range and comparatively blurred projection images, i.e., of a lower resolution. Another one is responsible for those small range and clear projection images, i.e., of a higher resolution.
For convenience of operation, such as moving a digital document, the digital table provides two pens respectively for two different detection systems. This requires the two detection systems won't be interfered one by another. As such, as taught thereby, one pen is a supersonic pen for moving digital documents, and the other one is an electromagnetic pen for writing on the documents.
However, according to the conventional digital table, the projection sources are all disposed above and in front of the table, and thus demanding too much space for operation and installment of the whole system. Meanwhile, in operation with such projection sources, displayed images are often sheltered by a hand or an arm of the user. When a part of an image is projected on the hand or the arm, viewers are very likely to feel uncomfortable about that. Furthermore, according to the conventional digital table, the projection position corresponding to the high resolution is fixed. However users often hope to view images with a high resolution at other areas of the digital table, and unfortunately this is not feasible according to the conventional digital table.